Liquid compositions containing surfactants, for example, shampoos, dishwashing liquids and other personal care, home care and industrial products, typically contain thickeners to increase the viscosity of the liquid compositions sufficiently to enable convenient handling. Often, the thickeners comprise an alkoxylated polyol containing lipophilic substituents, for example, ethoxylated methyl glucose esterified with a fatty acid. Such thickeners are typically alkoxylated to an extent sufficient to provide water-solubility and provide viscosification to the liquid surfactant composition. The lipophilic substituent, for example, fatty acid, typically provides associative thickening characteristics to the thickener.
Often, the thickeners are introduced to the liquid surfactant compositions in solid form and mixed under conditions effective to dissolve the thickener into the liquid surfactant composition and cause significant viscosity increases, for example, up to about 2,000 to 100,000 centipoise (cP) or higher. Frequently, the mixing must be conducted at elevated temperatures in the range of about 50° C. to about 80° C. in order to promote the dissolution of the thickener and obtain the desired viscosity enhancement (known in the art as “hot processing”). However, formulators of products comprising thickened, surfactant-containing liquids, for example, shampoos, desire the ability to formulate their products at ambient temperatures generally in the range of about 20° C. to about 30° C. (known in the art as “cold processing”). Additionally, formulators also desire thickeners which can be introduced to the liquid surfactant compositions in a liquid form rather than a solid form. The ability to introduce the thickener in a liquid form can provide a formulator with a greater degree of accuracy in introducing the correct amount of thickener to the liquid surfactant system and also better facilitate automated processing.
Given the above, there is a need in the art for improved compositions suitable for use as thickeners in liquid surfactant systems. In one embodiment, the thickeners can be introduced by cold processing and in a liquid state. Methods for using compositions to thicken liquid compositions comprising surfactants are also desired.